7.2 - RHSA-2015:1139

Problem Description:

Updated kernel-rt packages that fix multiple security issues, several bugs, and add various enhancements are now available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having Important security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.

2. Relevant releases/architectures:

Red Hat Enterprise Linux Realtime (v. 7) - noarch, x86_64

3. Description:

The kernel-rt packages contain the Linux kernel, the core of any Linux operating system.

* It was found that the Linux kernel's implementation of vectored pipe read and write functionality did not take into account the I/O vectors that were already processed when retrying after a failed atomic access operation, potentially resulting in memory corruption due to an I/O vector array overrun. A local, unprivileged user could use this flaw to crash the system or, potentially, escalate their privileges on the system. (CVE-2015-1805, Important)

* A race condition flaw was found in the way the Linux kernel keys management subsystem performed key garbage collection. A local attacker could attempt accessing a key while it was being garbage collected, which would cause the system to crash. (CVE-2014-9529, Moderate)

* A flaw was found in the way the Linux kernel's 32-bit emulation implementation handled forking or closing of a task with an 'int80' entry. A local user could potentially use this flaw to escalate their privileges on the system. (CVE-2015-2830, Low)

* It was found that the Linux kernel's ISO file system implementation did not correctly limit the traversal of Rock Ridge extension Continuation Entries (CE). An attacker with physical access to the system could use this flaw to trigger an infinite loop in the kernel, resulting in a denial of service. (CVE-2014-9420, Low)

* An information leak flaw was found in the way the Linux kernel's ISO9660 file system implementation accessed data on an ISO9660 image with RockRidge Extension Reference (ER) records. An attacker with physical access to the system could use this flaw to disclose up to 255 bytes of kernel memory. (CVE-2014-9584, Low)

* A flaw was found in the way the nft_flush_table() function of the Linux kernel's netfilter tables implementation flushed rules that were referencing deleted chains. A local user who has the CAP_NET_ADMIN capability could use this flaw to crash the system. (CVE-2015-1573, Low)

* An integer overflow flaw was found in the way the Linux kernel randomized the stack for processes on certain 64-bit architecture systems, such as x86-64, causing the stack entropy to be reduced by four. (CVE-2015-1593, Low)

Red Hat would like to thank Carl Henrik Lunde for reporting CVE-2014-9420 and CVE-2014-9584. The security impact of CVE-2015-1805 was discovered by Red Hat.

The kernel-rt packages have been upgraded to version 3.10.0-229.7.2, which provides a number of bug fixes and enhancements over the previous version, including:

* storvsc: get rid of overly verbose warning messages * storvsc: force discovery of LUNs that may have been removed * storvsc: in responce to a scan event, scan the hos * storvsc: NULL pointer dereference fix * futex: Mention key referencing differences between shared and private futexes * futex: Ensure get_futex_key_refs() always implies a barrier * kernel module: set nx before marking module MODULE_STATE_COMING * kernel module: Clean up ro/nx after early module load failures * btrfs: make xattr replace operations atomic * megaraid_sas: revert: Add release date and update driver version * radeon: fix kernel segfault in hwmonitor

(BZ#1223955)

Bug fix:

* There is an XFS optimization that depended on a spinlock to disable preemption using the preempt_disable() function. When CONFIG_PREEMPT_RT is enabled on realtime kernels, spinlocks do not disable preemption while held, so the XFS critical section was not protected from preemption. Systems on the Realtime kernel-rt could lock up in this XFS optimization when a task that locked all the counters was then preempted by a realtime task, causing all callers of that lock to block indefinitely. This update disables the optimization when building a kernel with CONFIG_PREEMPT_RT_FULL enabled. (BZ#1223955)

All kernel-rt users are advised to upgrade to these updated packages, which correct these issues and add these enhancements. The system must be rebooted for this update to take effect.

4. Solution:

Before applying this update, make sure all previously released errata relevant to your system have been applied.

For details on how to apply this update, refer to:

https://access.redhat.com/articles/11258

5. Bugs fixed (https://bugzilla.redhat.com/):

1175235 - CVE-2014-9420 Kernel: fs: isofs: infinite loop in CE record entries 1179813 - CVE-2014-9529 kernel: use-after-free during key garbage collection 1180119 - CVE-2014-9584 kernel: isofs: unchecked printing of ER records 1190966 - CVE-2015-1573 kernel: panic while flushing nftables rules that reference deleted chains. 1192519 - CVE-2015-1593 kernel: Linux stack ASLR implementation Integer overflow 1202855 - CVE-2015-1805 kernel: pipe: iovec overrun leading to memory corruption 1208598 - CVE-2015-2830 kernel: int80 fork from 64-bit tasks mishandling 1212083 - kernel-rt: rebase to the RHEL7.1.z batch3 source tree